/*
 * Copyright (c) 2003-2008 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors 
 *   may be used to endorse or promote products derived from this software 
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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package com.jme.scene.shape;

import java.io.IOException;
import java.nio.IntBuffer;

import com.jme.math.FastMath;
import com.jme.math.Vector3f;
import com.jme.scene.TexCoords;
import com.jme.scene.TriMesh;
import com.jme.util.export.InputCapsule;
import com.jme.util.export.JMEExporter;
import com.jme.util.export.JMEImporter;
import com.jme.util.export.OutputCapsule;
import com.jme.util.geom.BufferUtils;

/**
 * <code>PQTorus</code> generates the geometry of a parameterized torus, also
 * known as a pq torus.
 * 
 * @author Joshua Slack, Eric Woroshow
 * @version $Id: PQTorus.java,v 1.17 2007/09/21 15:45:27 nca Exp $
 */
public class PQTorus extends TriMesh {

    private static final long serialVersionUID = 1L;

    private float p, q;

    private float radius, width;

    private int steps, radialSamples;

    public PQTorus() {
    }

    /**
     * Creates a parameterized torus. Steps and radialSamples are both degree of
     * accuracy values.
     * 
     * @param name
     *            The name of the torus.
     * @param p
     *            The x/z oscillation.
     * @param q
     *            The y oscillation.
     * @param radius
     *            The radius of the PQTorus.
     * @param width
     *            The width of the torus.
     * @param steps
     *            The steps along the torus.
     * @param radialSamples
     *            Radial samples for the torus.
     */
    public PQTorus(String name, float p, float q, float radius, float width,
            int steps, int radialSamples) {
        super(name);

        this.p = p;
        this.q = q;
        this.radius = radius;
        this.width = width;
        this.steps = steps;
        this.radialSamples = radialSamples;

        setGeometryData();
        setIndexData();
    }

    private void setGeometryData() {
        final float THETA_STEP = (FastMath.TWO_PI / steps);
        final float BETA_STEP = (FastMath.TWO_PI / radialSamples);

        Vector3f[] toruspoints = new Vector3f[steps];
        // allocate vertices
        setVertexCount(radialSamples * steps);
        setVertexBuffer(BufferUtils.createVector3Buffer(getVertexCount()));

        // allocate normals if requested
        setNormalBuffer(BufferUtils.createVector3Buffer(getVertexCount()));

        // allocate texture coordinates
        getTextureCoords().set(0,
                new TexCoords(BufferUtils.createVector2Buffer(getVertexCount())));

        Vector3f pointB = new Vector3f(), T = new Vector3f(), N = new Vector3f(), B = new Vector3f();
        Vector3f tempNorm = new Vector3f();
        float r, x, y, z, theta = 0.0f, beta = 0.0f;
        int nvertex = 0;

        // Move along the length of the pq torus
        for (int i = 0; i < steps; i++) {
            theta += THETA_STEP;
            float circleFraction = ((float) i) / (float) steps;

            // Find the point on the torus
            r = (0.5f * (2.0f + FastMath.sin(q * theta)) * radius);
            x = (r * FastMath.cos(p * theta) * radius);
            y = (r * FastMath.sin(p * theta) * radius);
            z = (r * FastMath.cos(q * theta) * radius);
            toruspoints[i] = new Vector3f(x, y, z);

            // Now find a point slightly farther along the torus
            r = (0.5f * (2.0f + FastMath.sin(q * (theta + 0.01f))) * radius);
            x = (r * FastMath.cos(p * (theta + 0.01f)) * radius);
            y = (r * FastMath.sin(p * (theta + 0.01f)) * radius);
            z = (r * FastMath.cos(q * (theta + 0.01f)) * radius);
            pointB = new Vector3f(x, y, z);

            // Approximate the Frenet Frame
            T = pointB.subtract(toruspoints[i]);
            N = toruspoints[i].add(pointB);
            B = T.cross(N);
            N = B.cross(T);

            // Normalise the two vectors before use
            N = N.normalize();
            B = B.normalize();

            // Create a circle oriented by these new vectors
            beta = 0.0f;
            for (int j = 0; j < radialSamples; j++) {
                beta += BETA_STEP;
                float cx = FastMath.cos(beta) * width;
                float cy = FastMath.sin(beta) * width;
                float radialFraction = ((float) j) / radialSamples;
                tempNorm.x = (cx * N.x + cy * B.x);
                tempNorm.y = (cx * N.y + cy * B.y);
                tempNorm.z = (cx * N.z + cy * B.z);

                getNormalBuffer().put(tempNorm.x).put(tempNorm.y).put(
                        tempNorm.z);

                tempNorm.addLocal(toruspoints[i]);
                getVertexBuffer().put(tempNorm.x).put(tempNorm.y).put(
                        tempNorm.z);

                getTextureCoords().get(0).coords.put(radialFraction).put(
                        circleFraction);

                nvertex++;
            }
        }
    }

    private void setIndexData() {
        IntBuffer indices = BufferUtils.createIntBuffer(6 * getVertexCount());

        for (int i = 0; i < getVertexCount(); i++) {
            indices.put(i);
            indices.put(i - radialSamples);
            indices.put(i + 1);

            indices.put(i + 1);
            indices.put(i - radialSamples);
            indices.put(i - radialSamples + 1);
        }

        for (int i = 0, len = indices.capacity(); i < len; i++) {
            int ind = indices.get(i);
            if (ind < 0) {
                ind += getVertexCount();
                indices.put(i, ind);
            }
            if (ind >= getVertexCount()) {
                ind -= getVertexCount();
                indices.put(i, ind);
            }
        }
        indices.rewind();

        setIndexBuffer(indices);
    }

    public void write(JMEExporter e) throws IOException {
        super.write(e);
        OutputCapsule capsule = e.getCapsule(this);
        capsule.write(p, "p", 0);
        capsule.write(q, "q", 0);
        capsule.write(radius, "radius", 0);
        capsule.write(width, "width", 0);
        capsule.write(steps, "steps", 0);
        capsule.write(radialSamples, "radialSamples", 0);

    }

    public void read(JMEImporter e) throws IOException {
        super.read(e);
        InputCapsule capsule = e.getCapsule(this);
        p = capsule.readFloat("p", 0);
        q = capsule.readFloat("q", 0);
        radius = capsule.readFloat("radius", 0);
        width = capsule.readFloat("width", 0);
        steps = capsule.readInt("steps", 0);
        radialSamples = capsule.readInt("radialSamples", 0);

    }
}